Características dos gametas e primeiros estágios do desenvolvimento embrionário de curimatã comum (Prochilodus brevis, Steindachner, 1875)

Abstract

Brazilian Bocachico (Prochilodus brevis) is a rheophilic fish that needs to migrate to reproduce. However, the reproduction of this species is threatened by the construction of dams, overfishing and pollution of rivers. To solve this problem, it is necessary to know better the elements of the reproductive biology of these animals, aiming at the development of biotechniques that can help in the maintenance of natural stock of this species. Thus, the objective of this work was to describe the gametes of Brazilian Bocachico (P.brevis) and the beginning of the embryonic development in laboratory conditions. For that, samples of semen and oocytes from three males and two females of P.brevis, respectively, were collected from the breeding stock of the Laboratório de Biotecnologia da Reprodução de Peixes, UECE. After the collection, a semen pool was made from the samples collected from the three males that was evaluated for motility, morphology, membrane integrity and concentration. Oocytes were weighed and the concentration of the two females was estimated. In addition, these cells were evaluated for color, shape, adhesiveness and hydration capacity. Dry fertilization was done (Fertilization rate of 360.000 sperm/oocytes), with the addition of 100 ml of tank water for sperm activation and oocyte hydration. The mixture was transferred to two incubators, each for each female. Embryos in different stages were photographed using a stereomicroscope and an average of eight embryos per stage was fixed in Formol: Citrate (1%) for the preparation of histological sections. The spermatozoa of P.brevis does not has acrosome and the oocytes are telocytes. The analyzed semen pool has 98% motile spermatozoa, 100% alive, concentration of 23.4 billion sptz/μl, with 69.5% spermatozoa with normal tails. Oocytes collected from both females had a mean concentration of 1165ovocytes/g and all were hydrated when mixed with water from the tank. The embryos of P.brevis presented the following stages of development at a temperature of 26, 30 ° C: Cleavages (20-90 MAF), Morula (90-130), Blastula (130-245 MAF), Gastrula (245-360 MAF), Organogenesis (435 MAF) and Hatching (1065 MAF), totaling 16 hours 45 minutes of development. With this, it can be concluded that the gametes and the embryonic development of P.brevis follow the typical characteristics of teleosteos fish. This information opens up prospects for the development of new biotechniques that aim at the production of this species in captivity and its conservation.